PT 26 S3 Q18

A stingray without parasites is healthier than it would be if it had parasites.Nevertheless, ... ...

Which one of the following, if true, most helps to reconcile the discrepancy indicated above?
(A) During part of their life cycles, the parasites of stingrays require as hosts shrimp or oysters, which are environmentally vulnerable organisms.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Practice Set: "Resolve/Explain" Questions, Set 2 - Difficult/Uncommon Mix (25Q)